Problem: Determine how many solutions exist for the system of equations. ${-8x+2y = 8}$ ${y = 4+4x}$
Explanation: Convert both equations to slope-intercept form: ${-8x+2y = 8}$ $-8x{+8x} + 2y = 8{+8x}$ $2y = 8+8x$ $y = 4+4x$ ${y = 4x+4}$ ${y = 4+4x}$ ${y = 4x+4}$ Just by looking at both equations in slope-intercept form, what can you determine? ${y = 4x+4}$ ${y = 4x+4}$ Both equations have the same slope and the same y-intercept, which means the lines would completely overlap. ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ Since any solution of ${-8x+2y = 8}$ is also a solution of ${y = 4+4x}$, there are infinitely many solutions.